Genetically modified livestock

Cartoon illustrating genetic modification. The clippers represent an enzyme changing some base pairs in DNA.

Genetically modified livestock (GM livestock) are organisms from the group of cattle, sheep, pigs, goats, birds, horses and fish kept for human consumption, whose genetic material (DNA) has been altered using genetic engineering techniques. In some cases, the aim is to introduce a new trait to the animals which does not occur naturally in the species, i.e. transgenesis.

Terminology

Genetic modification is the direct manipulation of an organism's genome using biotechnology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms.

Transgenesis is the process of introducing a gene from another species — called a transgene — into a living organism so that the organism exhibits a new property and transmits that property to its offspring.

Pigs

In 2006, a pig was engineered to produce omega-3 fatty acids through the expression of a roundworm gene.[1]

Enviropig was a genetically enhanced line of Yorkshire pigs in Canada created with the capability of digesting plant phosphorus more efficiently than conventional Yorkshire pigs. The project ended in 2012.[2][3] These pigs produced the enzyme phytase, which breaks down the indigestible phosphorus, in their saliva. The enzyme was introduced into the pig chromosome by pronuclear microinjection. With this enzyme, the animal is able to digest cereal grain phosphorus.[2][4] The use of these pigs would reduce the potential of water pollution since they excrete from 30 to 70.7% less phosphorus in manure depending upon the age and diet.[2][4] The lower concentrations of phosphorus in surface runoff reduces algal growth, because phosphorus is the limiting nutrient for algae.[2] Because algae consume large amounts of oxygen, it can result in dead zones for fish.

Cattle

In 1990, the world's first transgenic bovine, Herman the Bull, was developed. At the early embryo stage, Herman was genetically engineered in a laboratory by Gen Pharm International. Scientists micro-injected cells with the human gene coding for lactoferrin. The Dutch Parliament changed law in December 1992 to allow Herman to reproduce. Eight calves were born in 1994 following a breeding program established at Gen Pharm's European laboratory. All calves inherited the lactoferrin production gene.[5] With subsequent sirings, Herman fathered a total of 83 calves.[6]

In 2011, Chinese scientists generated dairy cows genetically engineered with genes from human beings to produce milk that would be the same as human breast milk.[7] The researchers claim these transgenic cows to be identical to regular cows.[8] Two months later, scientists from Argentina presented Rosita, a transgenic cow incorporating two human genes, to produce milk with similar properties as human breast milk.[9] In 2012, researchers from New Zealand also developed a genetically engineered cow that produced allergy-free milk.[10]

Researchers have developed GM dairy cattle to grow without horns (sometimes referred to as "polled") which can cause injuries to farmers and other animals. The process is called genetic editing. A short strip of DNA was taken from the genome of Red Angus cattle, where it is known to suppress horn growth, and inserted into cells taken from an elite Holstein bull called "Randy". Each of the progeny will be a clone of Randy, but without his horns, and their offspring should also be hornless[11]

Goats

Goats have been genetically engineered to produce milk containing strong spiderweb-like silk proteins.[12]

Fish

Salmon

In November 2015, the FDA of the USA approved the GM AquAdvantage salmon created by AquaBounty for commercial production, sale and consumption.[13] It is the first genetically modified animal to be approved for human consumption. The fish is essentially a GM Atlantic salmon with a Chinook salmon (Oncorhynchus tshawytscha) gene inserted. This allows the fish to produce GH all year round for faster growth as the wild-type fish produces the hormone for only part of the year.[14] The fish also has a second gene inserted from the eel-like ocean pout that acts like an "on" switch for the hormone.[14] Pout also have antifreeze proteins in their blood, which allow the GM salmon to survive near-freezing waters and continue their development.[15] The wild-type salmon takes 24 to 30 months to reach market size (4–6 kg) whereas the producers of the GM salmon claim it requires only 18 months for the GM fish to achieve this.[15][16][17] It has been claimed that to prevent the genetically modified fish inadvertently breeding with wild salmon, all the fish will be female and reproductively sterile.[17] However, it has also been claimed that a small percentage of the females will remain fertile.[14] Some opponents of the GM salmon have dubbed it the "Frankenfish".[14][18]

Triploid rainbow trout and largemouth bass

Genetically modified triploid fish have been used to stock waterways for angling. Triploid fish are sterile (wildtype are diploid) and therefore their metabolism is targeted to growth rather than reproduction. They grow to large weights making them attractive to anglers. In 2008, the US state of Washington bought more than 40,000 triploid rainbow trout (Oncorhynchus mykiss)and stocked them in 95 inland lakes to increase fish-license sales. Triploid largemouth bass (Micropterus salmoides), a fish which is keenly sought by anglers, have also been developed.[19]

See also

References

  1. ↑ Lai L, et al. (2006). "Generation of cloned transgenic pigs rich in omega-3 fatty acids" (PDF). Nature Biotechnology. 24 (4): 435–436. PMC 2976610 Freely accessible. PMID 16565727. doi:10.1038/nbt1198. Archived from the original (PDF) on 2009-08-16. Retrieved 2009-03-29.
  2. 1 2 3 4 Guelph(2010). Enviropig. Canada:
  3. ↑ Schimdt, Sarah. "Genetically engineered pigs killed after funding ends", Postmedia News, 22 June 2012. Accessed 31 July 2012.
  4. 1 2 Canada. "Enviropig — Environmental Benefits | University of Guelph". Uoguelph.ca. Retrieved 8 March 2010.
  5. ↑ "Herman the bull - Herman becomes a father. "Biotech Notes."". U.S. Department of Agriculture. 1994.
  6. ↑ "Herman the bull heads to greener pastures". Expatica News. April 2, 2004.
  7. ↑ Gray,Richard(2011). "Genetically modified cows produce 'human' milk"
  8. ↑ Classical Medicine Journal (14 April 2010). "Genetically modified cows producing human milk.". Archived from the original on 2014-11-06.
  9. ↑ Yapp, Robin (11 June 2011). "Scientists create cow that produces 'human' milk". The Daily Telegraph. London. Retrieved 15 June 2012.
  10. ↑ Jabed, A.; Wagner, S.; McCracken, J.; Wells, D. N.; Laible, G. (2012). "Targeted microRNA expression in dairy cattle directs production of -lactoglobulin-free, high-casein milk". Proceedings of the National Academy of Sciences. 109 (42): 16811. Bibcode:2012PNAS..10916811J. doi:10.1073/pnas.1210057109.
  11. ↑ Hall, M. (April 28, 2013). "Scientists design ‘health and safety’ cow with no horns". The Telegraph. Retrieved December 18, 2015.
  12. ↑ Zyga, Lisa(2010). "Scientist bred goats that produce spider silk Archived April 30, 2015, at the Wayback Machine.".
  13. ↑ Commissioner, Office of the. "Press Announcements - FDA takes several actions involving genetically engineered plants and animals for food". www.fda.gov. Retrieved 2015-12-03.
  14. 1 2 3 4 "FDA: Genetically engineered fish would not harm nature". USA Today. 2012. Retrieved November 28, 2015.
  15. 1 2 Firger, J. (2014). "Controversy swims around genetically modified fish". CBS News. Retrieved November 28, 2015.
  16. ↑ Environmental Assessment for AquAdvantage Salmon
  17. 1 2 Steenhuysen, J.; Polansek, T. (November 19, 2015). "U.S. clears genetically modified salmon for human consumption". Reuters. Retrieved November 20, 2015.
  18. ↑ Connor S. (2012). "Ready to eat: the first GM fish for the dinner table". The Independent. Retrieved November 28, 2015.
  19. ↑ Merwin, J. (2009). "Trophy gluttony". Field and Stream. 103 (8).
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